Studies will be directed toward the in-vitro cultivation of Treponema pallidum and the comparative lipid composition and lipid metabolism of T. pallidum and cultivated treponemes. The use of fatty acids and phospholipids by treponemes will be studied. The mechanism of a commensal culture system involving two treponemes with similar lipid composition to that of T. pallidum will be investigated along with the ability of T. pallidum to grow in this culture system. All information on lipid studies will be applied to experiments designed to grow T. pallidum.